海洋水色遥感资料的经验正交函数分析

海洋中浮游植物进行光合作用,固定有机碳,是海洋生物链的基础,因此,研究浮游植物生物量的指标——光合色素(主要是叶绿素a)的时空变化具有十分重要的意义。我国自50年代以来,对海洋浮游植物色素分布进行了大量的现场调查和研究,取得了一些初步结果[1-3]。     

Seasonal and interannual variability of sea surface chlorophyll a concentration in the Japan/East Sea (JES)

Seasonal and interannual variability of chlorophyll a concentration in the Japan/East Sea (JES) was detected spatially by ocean color satellite remote sensing. Start timing of the spring bloom was different spatially. The spring bloom started at the subpolar front and southward of it in March, northward of subpolar front, along the Primorye coast and off Hokkaido in April and in the middle of the Japan Basin in May. The start of the spring bloom showed interannual variability that corresponded with the wind speed in the area. The spring bloom in 1998 and 2002 appeared about four weeks earlier than in 1997, 1999 and 2001, and it corresponded with weak winds that can lead to an early development of the thermocline. The bloom was late in 1999 and 2001 in the Japan Basin and along the Primorye coast, and in the southern area in 2000. It corresponded with stronger wind stress that delayed seasonal thermocline formation. The bloom along the Primorye coast appeared later in 1999, and it corresponded with stronger wind stress, and at the same time, it seemed to be related with the delay of melting of sea ice in Mamiya Strait. The fall bloom appeared from early October to early December, and it did not have a clear temporal transition. The area where chlorophyll a concentration exceeded 0.8 μg l⁻¹ was wider in the western area than in the eastern area every year. The magnitude of the fall bloom was different between years, but it did not show a correlation with average wind speed in fall. Those results indicated that the timing of the seasonal bloom in the JES is largely affected by the variability of global climate such as ENSO events.     

基于多源遥感数据的日本海内波特征研究

日本海特殊的地理位置和复杂的地形使得该海域内波表征极为复杂,遥感是大范围观测内波的有效手段,已被广泛应用于内波的探测研究。本文利用MODIS、GF-1和ENVISAT ASAR遥感影像,开展了日本海内波特征研究。通过提取内波波峰线,生成了日本海内波空间分布图;获取了内波的波峰线长度和传播速度,并基于非线性薛定谔方程反演了内波振幅。研究结果表明,日本海内波分布范围宽广,不仅大陆架沿海区内波分布密集,深海盆地也探测到了大量内波;日本海北部45°N附近海域有少量内波出现,利用高分影像探测到朝鲜陆架浅海区有大量小尺度内波,大和海盆、大和隆起的西南部海域没有发现内波。日本海内波波峰线长达100多千米,深海区的传播速度大于1 m/s;浅海区内波振幅约10 m左右,深海区可达60 m以上。     

The size-fractionated chlorophyll a and primary productivity in the Bering Sea during the summer of 2003

1Introduction Thephytoplanktonistheprimaryproducerofor- ganicsubstancesintheoceanandplaysanimportant roleinthesubstancecycleandenergyconversionof marineecosystem.Chlorophyllaconcentration(Chla) isanimportantindexmanifestingthelightenergy-au- totrophicbiomassinthesea.Primaryproductivityre- flectstheabilitytoconvertinorganiccarbonintoor- ganiccarbonbythephytoplanktonintheocean.Both Chlaandprimaryproductivityaretheimportantcon-tentsbeingstudiedinthemarineecosystemaswellas theimportantfoundationa…     

利用遥感技术估算南海北部表层异养细菌丰度

常规异养细菌监测方法精度高但费时费力且不能连续观测, 而卫星遥感成本低、可以大面积同步、长时间周期观测, 可与常规方法互补。文章利用南海北部10个航次采集的表层异养细菌丰度和卫星遥感反射率, 采用统计回归的方法建立了异养细菌丰度的遥感模型, 其模型决定系数为0.81, 均方根误差为2.44×10⁸个·L^-1, 平均相对误差为21%, 具有较好表现。利用该模型估算南海北部表层异养细菌丰度, 结果显示: 从珠江河口到南海北部开阔海域, 异养细菌丰度逐渐减小。夏季河口地区平均异养细菌丰度最高, 春季最低; 近岸海域靠近珠江河口西侧的平均异养细菌丰度高于东侧; 冬季陆架地区平均异养细菌丰度最高, 夏季最低; 开阔海域的异养细菌丰度变化幅度较小。     

基于遥感数据对比南海和阿拉伯海夏季叶绿素a浓度

The South China Sea(SCS) and the Arabian Sea(AS) are both located roughly in the north tropical zone with a range of similar latitude(0°–24°N). Monsoon winds play similar roles in the upper oceanic circulations of the both seas. But the distinct patterns of chlorophyll a(Chl a) concentration are observed between the SCS and the AS.The Chl a concentration in the SCS is generally lower than that in the AS in summer(June–August); the summer Chl a concentration in the AS shows stronger interannual variation, compared with that in the SCS; Moderate resolution imaging spectroradiometer(MODIS)-derived data present higher atmospheric aerosol deposition and stronger wind speed in the AS. And it has also been found that good correlations exist between the index of the dust precipitation indicated by aerosol optical thickness(AOT) and the Chl a concentration, or between wind and Chl a concentration. These imply that the wind and the dust precipitation bring more nutrients into the AS from the sky, the sub-layer or coast regions, inducing higher Chl a concentration. The results indicate that the wind velocity and the dust precipitation can play important roles in the Chl a concentration for the AS and the SCS in summer. However aerosol impact is weak on the biological productivity in the west SCS and wind-induced upwelling is the main source.     

基于TRMM卫星资料的渤海降水遥感估算研究

降水是全球能量平衡和水分循环中的关键要素,但海洋区域实时、准确的降水观测资料难以获取,因此,遥感卫星资料在海洋降水及全球能量和水分循环研究领域具有十分重要的应用前景。本文基于1998~2012年6个气象站点(岛屿或海岸带)的实测降水资料,评估TRMM(Tropical Rainfall Measuring Mission)V7版本3B42、3B43两个降水产品对渤海降水量的估算精度,在此基础上,分析并揭示渤海区域年、季和月降水量的时空特征。结果表明:在日尺度,3B42产品对渤海降水量的估算效果总体较差,而在月、年尺度,3B42、3B43产品与实测降水量比较接近,而且,3B43产品的估算精度稍高;总体上,TRMM表现出低估降水的特点,且当实测月降水量大于300 mm时,这种特征尤为显著;1998~2012年,渤海年降水量表现出明显的年际丰枯变化特征,多年均值为631.6 mm;夏季降水量占年降水总量的62.0%,7月是降水量最丰富的月份;空间上,渤海中南部降水量相对较高,而近岸区域降水量相对较低;受大气环流等因素的影响,夏季降水量重心向西北方向偏移,冬季则向东南方向偏移。     

2008年夏季白令海粒度分级叶绿素a和初级生产力

2008年7月我国第三次北极科学考察中在白令海不同区域设立BR断面、NB断面和BS断面,对200 m以浅海水进行叶绿素a浓度和初级生产力的现场观测,对部分观测站进行微型、微微型光合浮游生物的粒级结构分析,结果表明,在白令海叶绿素a和初级生产力区域性特征明显,深海海盆中BR断面表层叶绿素a浓度为0.190～0.976μg...     

基于EOF分析对南海西北海域水体光谱特性的研究

This study presents an analysis of the spectral characteristics of remote sensing reflectance(R_(rs)) in northwestern South China Sea based on the in situ optical and water quality data for August 2018.R_(rs)was initially divided into four classes,classes A to D,using the max-classification algorithm,and the spectral properties of whole R_(rs) were characterized using the empirical orthogonal function(EOF) analysis.Subsequently,the dominant factors in each EOF mode were determined.The results indicated that more than 95% of the variances of R_(rs) are partly driven by the back-scattering characteristics of the suspended matter.The initial two EOF modes were well correlated with the total suspended matter and back-scattering coefficient.Furthermore,the first EOF modes of the four classes of R_(rs)(A-D R_(rs)-EOF_1) significantly contributed to the total variances of each R_(rs) class.In addition,the correlation coefficients between the amplitude factors of class A-D R_(rs)-EOF_1 and the variances of the relevant water quality and optical parameters were better than those of the unclassified ones.The spectral shape of class AR_(rs)-EOF_1 was governed by the absorption characteristic of chlorophyll a and colored dissolved organic matter(CDOM).The spectral shape of class B R_(rs)-EOF_1 was governed by the absorption characteristic of CDOM since it exhibited a high correlation with the absorption coefficient of CDOM(a_g(λ)),whereas the spectral shape of class C R_(rs)-EOF_1 was governed by the back-scattering characteristics but not affected by the suspended matter.The spectral shape of class D R_(rs)-EOF_1 exhibited a relatively good correlation with all the water quality parameters,which played a significant role in deciding its spectral shape.     

Migration dynamics of Pacific herring (Clupea pallasii) and response to spring environmental variability in the southeastern Bering Sea

In the southeastern Bering Sea, Pacific herring (Clupea pallasii) migrate from the Pribilof Islands region where they overwinter, to the Alaska coast where they spawn in spring. The migration sustains a nearshore commercial fishery that targets roe-bearing females just prior to spawning. Herring also are taken as bycatch in groundfish trawl fisheries, where time and area closures in these fisheries are triggered by herring bycatch caps. Using herring bycatch data collected since the 1970s by National Marine Fisheries Service (NMFS) observers aboard groundfish fishing vessels, a retrospective analysis was conducted to describe the seasonal migration pattern of Pacific herring in the southeastern Bering Sea and to study its spatial and temporal variability. Observed changes in herring catch per unit of effort were compared with variability in climate and oceanographic conditions. The seasonal migration is complex, but annual shifts in migration routes and a possible northward shift of the overwintering grounds was identified. Pre-spawning herring aggregated in different areas depending on whether spawning occurred early or late in spring. The thermal structure of the ocean around the ice edge appears to influence herring migration timing and route as well as spawning date. Thus, on the basis of recent changes in sea-ice extent and duration, we suggest that the herring bycatch savings area that was developed from data collected in the 1980s should be revised to reflect prevailing conditions.     

Declined trends of chlorophyll a in the South China Sea over 2005-2019 from remote sensing reconstruction

Chlorophyll a concentration(CHL) is an important proxy of the marine ecological environment and phytoplankton production.Long-term trends in CHL of the South China Sea(SCS) reflect the changes in the ecosystem’s productivity and functionality in the regional carbon cycle.In this study,we applied a previously reconstructed15-a(2005-2019) CHL product,which has a complete coverage at 4 km and daily resolutions,to analyze the longterm trends of CHL in the SCS.Quantile regression was used to elaborat...     

Community structure and spatial distribution of macrobenthos in the shelf area of the Bering Sea

Field investigations of marine macrobenthos were conducted at ten sites in the Bering Sea in July 2010. Altogether 90 species of macrobenthos belonging to 59 families and 78 genera were identified. Among them, 41 polychaetes, 16 mollusks, 23 crustaceans, three echinoderms, two cnidarians, one nemertean, one priapulid, two sipunculids, and one echiuran were identified. The average density and biomass of total macrobenthos were 984 ind./m2 and 1 207.1 g/m2 of wet weight, respectively. The predominant species in the study area were Scoloplos armiger, Eudorella pacifica, Ophiura sarsii, Heteromastus filiformis, Ennucula tenuis, and Harpiniopsis vadiculus by abundance, while the predominant species in this area was Echinarachnius parma by biomass. Hierarchical cluster analysis(Bray–Curtis similarity measure) revealed that two important benthic assemblages in the study area were Community A and Community B. Community A was stable and Community B was unstable, as shown by the Abundance/Biomass Comparisons(ABC) approach. The macrobenthic community structure in the shelf of the Bering Sea was characterized by its high abundance and biomass, high productivity but great heterogeneity.     

基于空间自相关分析方法的渤海湾赤潮遥感叶绿素浓度研究

引入地学统计学中的空间数据分析方法,利用探索性分析、全局空间自相关和局部空间自相关分析对渤海湾赤潮爆发前后的遥感叶绿素浓度数据进行了研究。结果表明,渤海湾叶绿素浓度在相邻空间位置上具有高度的正空间自相关性;赤潮前渤海湾叶绿素浓度整体较低,但局部地区的叶绿素浓度表现出较大的上升随后几天又出现下降的异常现象;叶绿素浓度的全局空间自相关指数Moran's I值在赤潮爆发前变化幅度不大,在赤潮期间表现出一些不规则的异常变化;局部Moran's I的高-高型聚集在赤潮前主要分布在渤海湾南半部,赤潮期间出现分散并逐步转移到离岸区域,赤潮后期聚集在近岸区域。分析了其中的一些变化特征及异常情况,这些异常现象有可能是赤潮发生的预兆性信号,可为赤潮预报与应急提供一种新的尝试性模式。     

基于多源卫星遥感数据的安达曼海及其邻近海域内波分布特征分析

安达曼海是内波频繁发生的海区之一,对其内波的研究是当今海洋研究的热点。本文利用2013—2016年间覆盖整个安达曼海的3 000多幅Terra/Aqua MODIS、GF-1、Landsat-8、Sentinel-1 等卫星遥感图像,从中提取和解译了内波波列线和波向信息,得到安达曼海海洋内波的时间分布特征,并绘制了内波空间分布图。结果表明,安达曼海及其邻近海域内波主要出现在4个区域:苏门答腊岛以北海域、安达曼海中部海域、安达曼海北部海域以及尼科巴群岛以西海域,尺度较大的内波主要分布在苏门答腊岛以北海域和安达曼海中部海域。在时间分布上,2013—2016年间安达曼海内波的年发生次数相近;在热季、雨季及冬季遥感都能观测到内波的发生;2-4月遥感观测到的内波最多,其次为8、9月,7月遥感观测到的内波较少,这可能是由于雨季光学影像受云影响,安达曼海海域晴空影像过少造成,还需要借助更多的遥感影像进一步证明。在波向上,安达曼海多数内波向岸传播,在苏门答腊岛北部、安达曼海中部海域,内波向东或向东南传播;在安达曼群岛东部,内波向东传播,传播一定距离后与海底地形交互作用,一部分继续向前传播,一部分产生反射,向西南方向传播至安达曼群岛;在尼科巴群岛以西海域,内波由尼科巴群岛向孟加拉湾传播。     

Sound velocity and related properties of seafloor sediments in the Bering Sea and Chukchi Sea

The Bering Sea shelf and Chukchi Sea shelf are believed to hold enormous oil and gas reserves which have attracted a lot of geophysical surveys. For the interpretation of acoustic geophysical survey results, sediment sound velocity is one of the main parameters. On seven sediment cores collected from the Bering Sea and Chukchi Sea during the 5th Chinese National Arctic Research Expedition, sound velocity measurements were made at 35, 50, 100, 135, 150, 174, 200, and 250 k Hz using eight separate pairs of ultrasonic transducers. The measured sound velocities range from 1 425.1 m/s to 1 606.4 m/s and are dispersive with the degrees of dispersion from 2.2% to 4.0% over a frequency range of 35–250 k Hz. After the sound velocity measurements, the measurements of selected geotechnical properties and the Scanning Electron Microscopic observation of microstructure were also made on the sediment cores. The results show that the seafloor sediments are composed of silty sand, sandy silt, coarse silt, clayey silt, sand-silt-clay and silty clay. Aggregate and diatom debris is found in the seafloor sediments. Through comparative analysis of microphotographs and geotechnical properties, it is assumed that the large pore spaces between aggregates and the intraparticulate porosity of diatom debris increase the porosity of the seafloor sediments, and affect other geotechnical properties. The correlation analysis of sound velocity and geotechnical properties shows that the correlation of sound velocity with porosity and wet bulk density is extreme significant, while the correlation of sound velocity with clay content, mean grain size and organic content is not significant. The regression equations between porosity, wet bulk density and sound velocity based on best-fit polynomial are given.     

南海东北部基于标准经验算法的遥感叶绿素a反演结果比较分析

比较了2000年夏季邻近珠江口的南海东北部海区海洋水色传感器SeaWiFS遥感与走航叶绿素a(Chla)的分布,着重对比在运用Ruddick的浑浊水体大气校正方法的条件下OC2,OC4和OCTSC的3种标准经验算法反演的SeaWiFS遥感Chla与实测Chla偏离的相对程度。结果表明,3种产品都能够反映Chla从近岸向远岸降低的空间分布特征,但从近岸到远岸划分3个子区域分别对遥感与走航Chla求均值比较的结果表明。OC4产品偏离实测Chla分布的程度明显小于其他2种产品。此外3种产品的Chla频率分布差异显著。这一结果可以为选择适用于该海域海洋环境变动研究的SeaWiFS Chla标准产品提供参考。     

2008年夏季白令海陆架区微微型浮游植物分布及环境相关性分析

利用2008年夏季我国第3次北极科学考察资料,基于流式细胞技术,对白令海北部陆架区的微微型浮游植物丰度、细胞大小(碳含量)、色素浓度的分布特征进行了分析,并对该类群的环境适应性进行了研究.结果表明,微微型浮游植物中仅含聚球藻和真核藻,其丰度范围分别为0.14×106～2.69×106和0.23×106-12.49×10...     

Reconstruction of incomplete oceanographic data sets using empirical orthogonal functions: application to the Adriatic Sea surface temperature

A method for the reconstruction of missing data based on an EOF decomposition has been applied to a large data set, a test case of Sea Surface Temperature satellite images of the Adriatic Sea. The EOF decomposition is realised with a Lanczos method, which allows optimising computational time for large matrices. The results show that the reconstruction method leads to accurate reconstructions as well as a low cpu time when dealing with realistic cases. The method has been tested with different amounts of missing data, artificially adding clouds ranging from 40% to 80% of data loss, and then compared to the same data set with no missing data. A comparison with in situ data has also been made. These validation studies show that results are robust, even when the amount of missing data is very high. The reconstruction of the data from the Adriatic Sea shows realistic features and a reliable temperature distribution. In addition, the method is compared to an Optimal Interpolation reconstruction. The results obtained with both methods are very similar. The main difference is the computational time, which is reduced nearly 30 times with the method presented here. Once the reconstruction has been performed, the EOF decomposition is analysed to show the method’s reliability, and a cold event on the Albanian coast is studied. The reconstructed data reflect the effect of wind on the Albanian coast, that led to a cold-water episode in this zone for a 6-day period.     

Spatial variability in the partial pressures of CO2 in the northern Bering and Chukchi seas

In the summers of 1999 and 2003, the 1st and 2nd Chinese National Arctic Research Expeditions measured the partial pressure of CO₂ in the air and surface waters (pCO₂) of the Bering Sea and the western Arctic Ocean. The lowest pCO₂ values were found in continental shelf waters, increased values over the Bering Sea shelf slope, and the highest values in the waters of the Bering Abyssal Plain (BAP) and the Canadian Basin. These differences arise from a combination of various source waters, biological uptake, and seasonal warming. The Chukchi Sea was found to be a carbon dioxide sink, a result of the increased open water due to rapid sea-ice melting, high primary production over the shelf and in marginal ice zones (MIZ), and transport of low pCO₂ waters from the Bering Sea. As a consequence of differences in inflow water masses, relatively low pCO₂ concentrations occurred in the Anadyr waters that dominate the western Bering Strait, and relatively high values in the waters of the Alaskan Coastal Current (ACC) in the eastern strait. The generally lower pCO₂ values found in mid-August compared to at the end of July in the Bering Strait region (66–69°N) are attributed to the presence of phytoplankton blooms. In August, higher pCO₂ than in July between 68.5 and 69°N along 169°W was associated with higher sea-surface temperatures (SST), possibly as an influence of the ACC. In August in the MIZ, pCO₂ was observed to increase along with the temperature, indicating that SST plays an important role when the pack ice melts and recedes.     

空间变异对海洋叶绿素a质量浓度遥感产品精度验证的影响

海洋叶绿素a质量浓度遥感产品是海洋初级生产力与海洋生态系统固碳能力研究的重要数据源,为了保证数据的可靠性,对遥感产品进行精度验证以及验证误差的成因分析尤为重要.遥感产品的验证过程中,由于空间变异的存在,使得遥感像元尺度内的实测数据具有不同的离散程度和统计分布特征,并由此产生了不同的误差统计结果.本文选择MODIS-Aq...